<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
	<style type="text/less">
		@my:./img/1.png;
		@my1:"./img/1.png";
		@my2:'./img/1.png';
		@my3:'1.png';
		.app{
			.one{
				width: 125px;
				height: 37px;
				background: url(@my);
			}
			.two{
				width: 125px;
				height: 37px;
				background: url(@my1);
			}
			.three{
				width: 125px;
				height: 37px;
				background: url(@my2);
			}
			.four{
				width: 125px;
				height: 37px;
				background: url("./img/@{my3}");
			}
		}
	</style>
	<script src="lib/less.min.js"></script>
</head>
<body>
<div class="app">
	<div class="one"></div>
	<div class="two"></div>
	<div class="three"></div>
	<div class="four"></div>
</div>
</body>
</html>